1. Field of the Invention
The present invention relates to a communication control method preferably applied to a case where various information is transmitted by means of a wireless signal, for example, to construct a local area network (LAN) among a plurality of devices, and a transmission apparatus using this control method.
2. Description of the Related Art
Conventionally, in a relatively small range such as home, office or the like, when a local area network is constructed among a plurality of apparatus such as various video apparatus, a personal computer machine, its periphery apparatus or the like so as to transmit data handled by these apparatus, a wireless signal transmitter/receiver (a wireless transmission apparatus) is connected to each apparatus so as to enable data transmission through wireless transmission, instead of direct connection among apparatuses via a signal line.
A local area network is constructed through wireless transmission, thereby making it possible to simplify a system configuration without requiring direct connection among apparatus via a signal line or the like.
In the meantime, in the case where a local area network is constructed by using a plurality of wireless transmission apparatuses, if signals are transmitted simultaneously from a plurality of transmission apparatuses using a same transmission bandwidth, a transmission error may occur. Thus, communication among the respective transmission apparatuses in the network is required to access-control by means of any method.
As a conventionally known access control method, for example, in a small scale wireless network, there is exemplified a method for integrally managing communication among transmission apparatuses (nodes) in the network by means of a transmission apparatus (a route node) serving as a central part using a start-type connection.
However, to perform transmission processing using such star-type connection, it is presumed that a transmission apparatus serving as a central control station performing processing for transmission control is capable of performing wireless communication directly with all other transmission apparatuses in a network system. Therefore, there has been a problem that a wireless communication network construction range is limited within the range capable of directly making communication with the central control station; and the thus constructed network is available in a limited range, which depends on a transmission output of an electric wave of the central control station.
In addition, during transmission control processing using star-type connection, with respect to transmission control or network management also, in the case where direct communication with the central control station is disabled, it has been necessary to disconnect the corresponding transmission apparatus from the network. Therefore, there has been a problem that, in the case where a mobile station freely movable in the network is admitted as a transmission apparatus, control by the central control station becomes very complicated. That is, for the central control station to grasp a position of the mobile station, it has been necessary to transmit and receive a signal for connection check at a short period of time, and frequently supervise a connection state between the central control station and the mobile station.
To solve these problems, for example, it is considered to construct a distributed network configuration in which communication is made only between stations capable of performing direct communication instead of predetermination of the central control station. In the case of this distributed network, if a distance to a necessary destination station is distant, it is required to transmit data by relaying a number of stations. Every time such relaying is performed, it is required to perform processing for transmission start with the destination station for communication. As a result, there is a problem that data transmission is delayed every time the number of steps performing relaying is increased.
It is an object of the present invention to well control a station incapable of directly making communication with a control station in the case where an attempt is made to control communication in a network system by means of the control station.
As a first aspect of the present invention, there is provided a communication control method comprising:
specifying a frame period by means of a predetermined signal;
setting a management data transmission region in the frame period; and
when a common information to be transmitted from a control station is received by a plurality of communication stations, any of the communication stations repeatedly transmitting the received common information.
According to this communication control method, common information is repeatedly transmitted in a communication station other than the control station, thereby making it possible to receive the common information even in a communication station incapable of directly making communication with the control station.
As a second aspect of the present invention, there is provided a communication control method for controlling an access of wireless communication among a plurality of communication stations by means of a control station, said control method comprising:
specifying a frame period by a predetermined signal;
setting a management data transmission region in the frame period;
allocating a plurality of slots in the management data transmission region, the plurality of communication stations or a control station individually transmitting data concerning communication states in the respective stations; and
said control station recognizing the presence of a station incapable of directly making wireless communication based on a transmission state of data concerning the communication state.
According to this communication control method, the control station recognizes the presence of a station incapable of directly making wireless communication, and the control station can take action to execute communication control processing for the station.
As a third aspect of the present invention, there is provided a transmission apparatus comprising:
a timing setting means for setting a frame period based on a predetermined signal and setting a management transmission region in the frame period;
a receiving means for receiving management data to be transmitted from other transmission apparatuses in the management data transmission region; and
a transmitting means for transmitting common information in management data which said receiving means has received at a predetermined timing.
According to this transmission apparatus, the common information in the management data received by the receiving means can be transmitted from transmitting means to other transmission apparatuses.
As a fourth aspect of the present invention, there is provided a transmission apparatus comprising:
a timing setting means for setting a frame period based on a predetermined signal and setting a management data transmission region composed of a plurality of slots in the frame period;
a transmitting means for transmitting data on a state of communication with other transmission apparatuses in a predetermined slot in the management data transmission region;
a receiving means for receiving data in a slot other than said predetermined slots in said management data transmission region; and
a control means for recognizing the presence of a transmission apparatus incapable of directly making communication with said control apparatus from data on communication state which said receiving mean has received.
According to this transmission apparatus, the presence of a transmission apparatus incapable of directly making communication with the control apparatus is recognized, making it possible to handle the transmission apparatus.